src/it/projects/descriptor-refs/project/no-target-dir-multimodule/pom.xml

<?xml version='1.0' encoding='UTF-8'?>
<project xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd' xmlns='http://maven.apache.org/POM/4.0.0'>
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.apache.maven.plugin.assembly.test</groupId>
    <artifactId>it-project-parent</artifactId>
    <version>1</version>
  </parent>
  
  <groupId>test</groupId>
  <artifactId>multimodule-sources-copied</artifactId>
  <packaging>pom</packaging>
  <version>1.0-SNAPSHOT</version>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  
  <modules>
    <module>child1</module>
    <module>child2</module>
  </modules>
  
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <executions>
          <execution>
            <id>assembly</id>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
            <configuration>
              <descriptorRefs>
                <descriptorRef>project</descriptorRef>
              </descriptorRefs>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>